As technology moves toward faster utilization of devices, multifunction devices (MFDs), such as printer/fax/scanner devices, printers, and scanners, communication between the devices and computers becomes important. Additionally, the devices are being networked to provide utilization of the a limited number of devices by several computers at any given time. However, devices that are locally connected communicate differently compared to devices that are networked.
Networking several computers with devices reduces the capabilities of two way communication of data between the computers and the devices because of the way data is communicated through networking. Local communication of data between computers and devices provides a more direct two-way communication of data between computers and the devices.
A typical method for networking devices, such as printers, involves using a device server port monitor software to redirect device requests across the network. In other cases, a network driver allows printer ports to be redirected. In most situations, the printer driver sends the printing data to the port monitor or network redirection layer. The port monitor and layers below are responsible for ensuring the job is properly printed (the printer driver has totally completed its job and given the data to the port monitor).
Some device drivers bypass the port monitor interface and write directly to a communication layer. This allows for more direct manipulation of the device, but it usually means that the device can no longer be networked. As more people try to network these devices, the approach of bypassing the port monitor interface and writing directly to the communication layer becomes increasingly difficult. This approach is made even worse when device drivers bypass the communication layer entirely and send device data directly to the parallel port hardware, such as the Super I/O chip in the computer. If communication like this is required, the printer cannot be networked.
Additionally, if a device is networked, communication between more than one computer and the networked device is difficult due to the device being busy receiving a request from one of the computers. The other computers on the network must wait until the receiving of data by the networked device is complete.
Because of communicating locally is different from communicating across a network, devices for the network cannot be locally connected and local devices cannot be networked without difficulty.